16.8) 1) x²+18x+81-x²-8x=1;
10x=-80;
x=-8;
2) x²-22x+121=x²-9x-7x+63;
x²-x²-22x+9x+7x=63-121;
-6x=-58;
x=9 4/58=9 2/29;
3) x²-16-x²-12x-36=-16;
-12x=36;
x=3;
4) 1-6x+9x²-9x²+2x=5;
-4x=4;
x=-1;
16.6) 1) x²-24x+144+24x=x²+144;
2) x²+16x+64-x²-5x=11x+64;
3) 2x²+4x-x²+4x-4=x²+8x-4;
4) y²+14y+49+y²-7y+2y-14=2y²+9y+35;
5) a²-1-a²-8a-16=-8a-17;
6) 9x-90-x²+10x+x²+20x+100=39x+10